1. Field of the Invention
The present invention generally relates to local oscillator (LO) leakage signal reduction. More specifically, the present invention provides LO leakage signal cancellation using baseband DC offsets.
2. Background Art
Generally, a wireless radio frequency (RF) transmitter includes a baseband section and an RF section. Baseband information signals are generated and manipulated within the baseband section. The baseband information signals are up-converted and further manipulated within the RF section to produce a transmitter output signal.
Random device mismatches within the constituent components of the baseband section can produce DC offsets within the baseband information signals. These baseband DC offsets can be up-converted by the transmitter to produce a LO leakage signal. The LO leakage signal is an undesirable signal that can interfere with the subsequent detection and demodulation of the transmitter output signal.
The quality of the transmitter output signal suffers if a transmitter fails to compensate for the baseband DC offset component of a LO leakage signal. Many techniques to reduce a power of the LO leakage signal rely on complicated calibration circuits designed to compensate for baseband DC offsets. Such calibration circuits are often expensive in terms of required processing power and required additional components. Further, re-calibration of the compensation of baseband DC offsets is required every time the transmitter gain is changed or every time the transmitter operating point is changed. Consequently, design, manufacturing and operating costs of the transmitter are increased.